In the past, a common refrigerant used in refrigeration systems has been 1,1,1,2-tetrafluoroethane, which is commonly known as R134a. However, owing to the 15 high green house effect potential (GWP, Global Warming Potential) of R134a, it is not allowed to use R134a as a coolant in new vehicles anymore.
A substitute coolant, which is known as R1234yf and which has a permissible low GWP value has been developed, which, unfortunately, is inflammable. The service stations used for the filling, emptying and flushing of the new inflammable coolant must therefore fulfill the ATEX Directive 94/9/EU concerning equipment and protective systems intended for use in potentially explosive atmospheres or inflammable atmospheres. This EU directive, in short ATEX, implies that the service station used for the filling and emptying of NC systems, especially mobile A/C systems in vehicles, must comply with considerable technical requirements when the inflammable coolant is to be added to the NC system, or when service is performed on the NC systems containing the inflammable coolant.
In accordance with ATEX, a zone 2 is classified as an area in which, normally, no inflammable atmosphere is present—only in case of an accident, and then only briefly. Zone 2 is the lowest area classification according to ATEX.
A component which contains an inflammable medium and also has a connection or a gasket, which is not technically tight, is considered to have a zone 2 in a radius of 1 m around the connection or gasket. A gasket is normally tight, but may become leaky because of wear and/or ageing. Therefore, according to AT EX, a zone 2 atmosphere will by definition be present around the gasket.
When maintenance is performed on A/C systems, the coolant is evacuated from the A/C system prior to service or repair. The evacuation is normally performed by suction.
When performing service and/or repair on A/C systems operating with an inflammable coolant, the service systems must therefore be suitable for use in a zone 2 environment according to ATEX. In other words, zone 2 requirements should be fulfilled at least inside the service station.
In those cases where the A/C system includes components which are to be replaced, there is a procedure where the oil and/or particulates content in the component itself, or in the entire air conditioning system, has to be flushed out by means of a so-called flushing process. So far, so-called flushing kits have been used for this, said kits being supplied to the service stations as “add-ons” for mounting between the A/C system and the service station during the flushing process. With the prior art technology, as mentioned, the flushing kit is mounted between the mobile A/C system and the service station. The primary purpose of this flushing kit is to catch all the coolant which is flushed through the A/C system from the service station in liquid form, as well as the oil and any solids or particulates which are entrained by the flushing flow of the coolant. After collection, it is then the task of the service station to empty the coolant from the accumulator of the flushing kit in gas form, thereby leaving the oil in the accumulator. Conventional service stations for mobile for A/C systems usually contain their own suction accumulator, a heated suction accumulator, which basically has the same function as these flushing accumulators in the flushing kits—they are just smaller, since they are not intended to receive any large amounts of coolant and also just smaller amounts of oil when a normal service is carried out on a mobile A/C system, i.e., when the Me system is only to be emptied.
Since, however, the new coolant is inflammable, this flushing kit will have to comply with the special requirements in ATEX, which also apply to the service station, since a zone 2 will be present around every connection, i.e., also around the connections between the external flushing kit and the service station.
One possible solution would be to use only components suitable for explosive zones according to the requirements of the ATEX directive. This, however, would increase the costs of the refrigeration system considerably.